Remove IOThread::message_loop().

chrome/browser/process_singleton_linux.cc

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // On Linux, when the user tries to launch a second copy of chrome, we check
 // for a socket in the user's profile directory.  If the socket file is open we
 // send a message to the first chrome browser process with the current
 // directory and second process command line flags.  The second process then
 // exits.
 //
@@ skipping 977 matching lines @@
 
   if (bind(sock, reinterpret_cast<sockaddr*>(&addr), sizeof(addr)) < 0) {
     PLOG(ERROR) << "Failed to bind() " << socket_target_path.value();
     CloseSocket(sock);
     return false;
   }
 
   if (listen(sock, 5) < 0)
     NOTREACHED() << "listen failed: " << safe_strerror(errno);
 
-  // Normally we would use BrowserThread, but the IO thread hasn't started yet.
-  // Using g_browser_process, we start the thread so we can listen on the
-  // socket.
-  MessageLoop* ml = g_browser_process->io_thread()->message_loop();
-  DCHECK(ml);
-  ml->PostTask(FROM_HERE, base::Bind(
-    &ProcessSingleton::LinuxWatcher::StartListening,
-    watcher_.get(),
-    sock));
+  DCHECK(BrowserThread::IsMessageLoopValid(BrowserThread::IO));
+  BrowserThread::PostTask(
+      BrowserThread::IO,
+      FROM_HERE,
+      base::Bind(&ProcessSingleton::LinuxWatcher::StartListening,
+                 watcher_.get(),
+                 sock));
 
   return true;
 }
 
 void ProcessSingleton::Cleanup() {
   UnlinkPath(socket_path_);
   UnlinkPath(cookie_path_);
   UnlinkPath(lock_path_);
 }